Comparison of the effects of different powder distribution methods of espresso the best method of coffee powder distribution is beating

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The correct method of filling Italian Coffee Powder Press Coffee Powder

The experiment of testing different powder distribution methods is a difficult journey, and this article is to make you understand what happens in the short operation from bean grinder to espresso machine.

Earlier, I launched a questionnaire survey. For the results and discussion of the questionnaire, please poke here. This article is like a pseudoscience paper. The reason why it is not written strictly according to the format and writing of the scientific paper is that I think it is easy to read and understand. In other words, I think it is very important to write my experimental article in such an easy way.

Abstract

The test I did may seem a little strange at first, but I promise it will be a delicate and meaningful indicator. In essence, this test measured the ability of a powder distribution method to steadily and evenly distribute coffee powder of a certain quality in a fixed capacity powder bowl.

Brief introduction

As mentioned in the previous article, the evaluation of powder distribution methods should be based on the quality, consistency, speed and cleanliness of the extraction. It is also difficult and time-consuming to test all the powder distribution methods at once. So I will break down one by one and use a series of tests to help understand. The most basic way to spread the powder is to try to distribute the coffee powder evenly in the powder bowl. The result should be that the density of coffee powder is the same everywhere in the powder bowl. The process of trying to reach the "maximum uniformity limit" is the best part of the test, because it will never be "too uniform", which is endless. Once we understand this, it becomes very easy to design a test to measure uniformity.

Materials and methods

The test I designed was so simple that it didn't even need to actually brew coffee, just to test the uniformity and consistency of coffee powder in the powder bowl. My operation is as follows: I chose the three most representative ideas from a variety of powder distribution methods. The reason for this is that many methods are actually very similar, which can save time.

1. Direct filling and pressing

-pick up the powder from the bean grinder and move the brewing handle so that the coffee powder falls into the powder bowl as evenly as possible

-then tap the cooking handle twice on the powder rack.

-fill in and press.

2. Wipe the surface of the coffee powder evenly with your hand / palm / tool. Here I choose to use the Stockfleth method that I use most easily. )

-pick up the powder from the bean grinder and move the brewing handle so that the coffee powder falls into the powder bowl as evenly as possible

-then tap the cooking handle twice on the powder rack.

-turn the fingers and the brewing handle to make the coffee powder on the surface very smooth and uniform

-fill in and press.

3. Knock up and down and tap horizontally

-pick up the powder from the bean grinder and move the brewing handle so that the coffee powder falls into the powder bowl as evenly as possible

-then tap the cooking handle twice on the powder rack.

-Pat the side of the cooking handle with your palm until the coffee powder in the powder bowl is highly consistent.

-fill in and press.

In each of the above three processes, I used a slight excess of coffee powder (0.5-1g more than my goal of 20.8g), then used their own cloth method to distribute the powder, and then filled it very hard until the coffee powder could no longer be compressed. This is much more powerful than it takes me to actually brew coffee at the bar, because I need to exclude this variable, and different filling pressure will lead to different coffee powder density. Here is a simple explanation.

As shown in the picture, when you fill it, a small difference in pressure can make a big difference in the density of coffee powder. When moderate or "standard" pressure is used, this effect can be weakened, and if the powder is pressed very hard, the effect is almost negligible. After exceeding a certain point, no matter how hard the pressure is, the density will not change. That's why I packed so hard-this removes the variable that affects the density of coffee powder from the test. What I want to test is the advantages and disadvantages of a method of cloth powder. To do this, I need to get the same volume of coffee pressed powder for each test and weigh it. The quality of coffee powder in this volume can indicate the uniform distribution of coffee powder. As mentioned earlier, I will add an extra 0.5-1g of coffee powder to each handle. In this way, the coffee powder in the powder bowl is excessive. In order to get the same volume of coffee pressed powder, I used a high-precision horizontal spatula, and the depth of the scraper depends on the edge of the powder bowl, that is, turning to the scraper will scrape out a certain depth (0.5-1mm) of coffee powder very smoothly. Finally, I will weigh the remaining coffee powder in the powder bowl.

Excess coffee powder accounts for less than 5% of the total mass. From this simple experiment, I can quickly and easily measure the amount of coffee powder left in multiple powder bowls, thus summing up the consistency.

Test result

The following are the test results of three powder distribution methods, 15 samples for each method.

From the results, it is clear that tapping up and down and horizontal tapping (purple) is the best consistent method of powder distribution. Another very obvious conclusion is that manually wiping the surface of coffee powder (Stockfleth method: red) is more consistent than directly filling (cyan). I will add some data below to make it easier to understand. I will calculate the average value of each powder distribution method, and then calculate the consistency of each method according to the average. I like to measure consistency with standard deviation best. The standard deviation is a measure of the extent to which the data deviate from the arithmetic mean. In this experiment, the greater the standard deviation, the worse the consistency.

Discuss

If the weight of the coffee powder left over from several brewing handles in the experiment is very similar, I think it can be said that this cloth method can distribute the powder consistently. If the weight of the remaining coffee powder varies, that means there are lower / higher density areas in the pressed powder, which speeds up / slows down the flow. So inconsistency doesn't just mean inconsistency, it shows that some areas of pressed powder are uneven. Naturally, it can be speculated that a more uniform density of coffee powder will make the flow velocity through the entire coffee pressed powder more uniform, and the extraction of the product will be more uniform. There are only 45 samples in this test, and the more samples you have, the more accurate the results will be. However, I am glad that different methods of powder distribution do have different results. If there is no difference, then I have to collect more experimental results. The addition of averages also adds an interesting element to the experiment. The median value of the cloth powder method is 0.2g higher than the other two, and I don't know why, but my personal understanding is that the maximum amount of coffee powder that can be filled in a certain volume is sometimes not very uniform.

Conclusion

The conclusion drawn from this small number of experimental samples is that tapping is the most consistent method of powder distribution. The Stockfleth method is better than directly filling. This does not mean that slapping is the ultimate method of powder distribution. With the development of science and technology, it will certainly lead to better methods of powder distribution, and the ultimate goal of this experiment is to provide you with a way of thinking and ways to examine the skills you use to make coffee. Coffee is a never-ending road!

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